| 摘要 |
A sleeve consisting of a material which will not bond to the injection moulding for which it forms the core, has a sprial groove on its outer surface in which a resistance wire is wound. The moulding forms a coupling for pipes etc. to which it can be welded when an electric current is laid on to the coil. A number of lengthways extending grooves intersect the spiral groove, so that bridges are formed in the moulding which hold the wires immovably in place, when the core is extracted. For pref. the lengthways grooves intersect the spiral grooves at an angle. They may be interrupted and they are near enough equal to the depth at which the inner faces of the coil wires are located. The core is a thin walled sleeve which can be removed by deformation or by breaking into pieces. To provide couplings which accurately weld the components together without danger of shortcircuiting, and in which the wires, although they are at the inner surface of the socket, cannot be displaced by rough treatment or careless handling. |
